The present invention relates to a new and improved method of, and apparatus for, processing a signal containing pulses which have been distorted by a preceding signal transmission or transfer operation undertaken on an original non-distorted pulsed signal.
A method and an apparatus such as known, for example, from European Patent Publication No. 0,148,413 permits correcting faults in signals which are transmitted in the form of pulses, for example, by means of a magnetic record carrier. During the operation of such method and apparatus there are particularly corrected the running lengths or pulse widths or pulse durations of the pulses between successive pulse edges or flanks. For this purpose there are firstly determined the deviations of the signal with respect to the running lengths or pulse widths. Such deviations are stored. Subsequently the input signals are directly processed to produce output signals by combining the stored signal deviations and the input signals, i.e. the running lengths or pulse widths of such input signals. The output signals are formed as a result of such combination.
A circuit for processing, particularly shaping or forming pulses is known, for example, from European Patent Publication No. 0,147,550. Using such circuit or circuit arrangement, deformed pulses or distorted signals can be altered in a manner such as to better correspond to the shape or form which has been originally intended, for example, after recording on a magnetic tape. In this known circuit or circuit arrangement there is detected and measured the temporal spacing between two successive pulses which represent data. This temporal spacing gives an indication of the magnitude of the pulse distortion. A correction signal is generated on the basis of the aforementioned measurement and the incoming pulses are shaped or formed in accordance with such correction signal.
The aforementioned apparatus according to European Patent Publication No. 0,148,413 must be prepared for its operation by loading storage means or memory devices with the signal deviations. Contrary thereto, the last-mentioned circuit or circuit arrangement according to European Patent Publication No. 0,147,550 can be immediately utilized without any particular preparation because this circuit or circuit arrangement is continuously adapted to the incoming signals.
The circuit or circuit arrangement according to European Patent Publication No. 0,147,550 has one disadvantage due to the fact that the input signal constitutes an analog input signal and is processed or altered in analog manner. There is thus attempted to adapt the analog input signal to the ideal and original analog signal. This adapting operation can only succeed to the extent that a more or less amplified correction signal is added to the analog input signal. If such addition is insufficient for achieving the desired correction, the possibilities rendered by such circuit or circuit arrangement are exhausted.
There is one disadvantage of the method and apparatus according to European Patent Publication No. 0,148,413 in that the correction of the determined running lengths or pulse widths is not affected in an adaptive fashion, and as a consequence, the correction is not continuously adapted to the signals being processed.